When it comes to moments for myself, I'm not asking for much. I'd like to get a haircut, lounge in the backyard with a book, maybe have dinner out with my husband. Luxuries? Hardly. And yet, with my mile-long to-do list, I can't get to them.

I'm not alone in feeling overscheduled and overstressed. In a new survey, 72 percent of women said they take on more than they can handle. And that doesn't just make us feel bad. "When we feel crushed by the weight of our obligations, we get sick," says Alice Domar, PhD, executive director of the Domar Center for Mind/Body Health.

Many studies show that stress dampens the immune system; a recent one found that it not only puts us at greater risk of a cold, but possibly even asthma or heart disease.

The solution—lightening your proverbial load—probably seems impossible. But not only will it buoy your immune system, it also can help you craft a life that's more fulfilling, with more time for activities you love—or even just time to do nothing. Follow these steps to learn how to shake off the dead weight—and feel infinitely more alive.

Ask Yourself: What's Weighing You Down?

Before you begin lightening up, you have to determine which of your to-do's are drags and which are actually want-to-do's. "What are the juicy pieces that might make your calendar look lighter if you said no to them, but wouldn't actually make you feel lighter?" asks Brene Brown, PhD, a research professor at the University of Houston Graduate College of Social Work and author of The Gifts of Imperfection. Here's how:

1. Take a frank look at everything on your schedule for the next week. Don't count nonnegotiable obligations like paying bills, doing laundry, or going to the dentist. For each activity, ask yourself: "When it's over, do I feel energized or depleted? How will I feel if I don't do it?"

2. Rate each activity that's within your control—from spin class to that money-management workshop, lunch with your old boss to baking for the neighborhood block party—on a scale of 1 to 10, with 10 being the most enjoyable, meaningful, or rewarding, and 1 being the least.

The more benefit you gain from an activity, the higher its rating. For example, you could stop planting pansies in your yard, but you'd miss smiling at those rich purple blooms in summer. You could stop leading your local Girl Scout troop, but you'd miss feeling like you're connecting with your daughter and making a difference in the world. Here's a sample list:

• Spin class = 8

• Baking cupcakes for the block party = 2

• Lunch with your old boss = 6

• Money-management class = 3

• Taking your mother-in-law shopping = 4

At first glance, spin class may seem like the most disposable item on the list, but you know if you don't go, you'll feel crabby and sluggish the rest of the week. On the other hand, if you bag making cupcakes for the block party (you could always pick up some store-bought ones, right?), you'll feel relieved to have your Sunday back. So spin class outranks baking cupcakes. "The load we need to lighten is those things that are serving other people at the expense of our own well-being," Brown says.

Just Say No

Grab a red pen and slash activities rated 1 or 2 right off your schedule. Does this involve turning someone down? Just saying "no" is, hands-down, the most effective way to do that. "No" is a complete sentence. Really! And it doesn't give any room for doubt or push back.

But if that feels too hard to say—or the person you're turning down is really persistent—here are ways to say it and feel better about it, from the firmest to the mildest:

• 'That's not really my speed.' A softer version of a hard no that still leaves no room for argument.

• 'Let me check my calendar and get back to you.' "It's hard to think on your feet," Domar says. "This gives you time to reflect." It also makes other people feel placated—and lets you decline later via email, which often feels easier than doing so face-to-face.

• 'No, but how about I drop off store-bought cupcakes another time?' Offering an alternative solution keeps you on the hook for the future, but it also puts you in control, so you're helping out on your own terms and not someone else's.

• 'No, because I'll be away on business/this is my busy time/I have a conflict.' This type of no gives a concrete reason why and takes the blame off you, so it's a tempting response. One problem, though: It opens up a hole for comebacks like, "Then we'll wait for you to get back into town!" Save this one for situations where bad timing really is the problem.

Peel the Onion

Sometimes we agree to tasks rated 3 through 5 even though they add to our already-heavy load. Why? Brown recommends "peeling the onion"—digging deep to understand your true motivation. Often, it comes from a personal priority or strength: Maybe you're devoted to family, so when you agree to pick up your mother-in-law from the airport, you're expressing a value that's important to you. Or maybe you're a whiz with words, so when you say you'll edit your friend's resume, you're seizing the chance to shine! Tasks become less burdensome when you recognize that they feed your soul in some way.

Aim for OK

Make this your goal for activities, rated 6 through 8, that you enjoy but don't have time to execute perfectly. "How good does something need to be?" Domar asks. "I'd rather have an employee turn in something on time that's just fine than turn in something a week late that's really good."

So host a party and buy appetizers at Costco instead of staying up all night cooking from scratch. Meet your old boss for lunch (and a little networking!), but go somewhere casual so restaurant service doesn't swallow up your day. "This frees you up to move on to the next thing," says Domar—even if that next thing is lying on the sofa zoning out to HGTV.

Make the Time

Taking a ceramics class, check! Meeting girlfriends for Friday happy hour, check! Activities rated 9 or 10 are things that give you true joy, and it's worth ditching the dead weight so you can make time for them. Don't ever feel guilty about these soul-nourishing activities: They'll see you through life's more tedious obligations, so even if you're technically super busy, your life will still feel light and full, all at the same time.